Reciprocating internal combustion (IC) engines are known for converting chemical energy stored in a fuel supply into mechanical shaft power. IC engines may use one or more fuel injectors to inject a quantity of combustible fuel into a variable volume defined by a piston translating within an engine cylinder. In turn, the injected fuel mixes with an oxidizer and burns within the variable volume to perform work on the piston. Fuel injectors may be used to inject fuel directly into a variable volume of an IC engine, inject fuel into an oxidizer flow upstream of a variable volume of an IC engine, or combinations thereof.
Solenoids have been used to electrically actuate fluid injectors, such as IC engine fuel injectors, whereby a current flowing through a stator coil creates a magnetic field that imparts a force on an armature. In turn, armature movement induced by the magnetic field may act to initiate a fuel injection event, end a fuel injection event, or tailor a flow rate of an ongoing fuel injection event. The effective stroke distance of the armature may be very small, and therefore, injector performance may be sensitive to tolerance stack-up among injector components, and may be sensitive to small armature movements caused by dynamic overtravel, for example.
U.S. Pat. No. 6,688,579 (the '579 patent), entitled “Solenoid Valve for Controlling a Fuel Injector of an Internal Combustion Engine,” purports to address the problems of armature bounce upon de-energizing the solenoid, and sensitivity to the precise setting of the maximum slide path which is to be available to an armature plate on an armature pin. The '579 patent describes a two-part armature including an armature plate decoupled from an armature pin. Further according to the '579 patent, an overtravel stop is arranged between the armature plate and a sliding sleeve, such that the overtravel stop delimits the maximum possible movement path of the armature plate on the armature pin, which is adjustable by an actuator. The actuator of the '579 patent is implemented as a screw element provided with an internal thread that is screwed onto an external thread of the armature plate, such that relative rotational motion between the actuator and the armature plate varies the maximum possible movement path of the armature plate on the armature pin.
However, the screw-type adjustment of maximum axial movement between the armature plate and the armature pin in the '579 patent may pose repeatability and reproducibility challenges upon assembly, in addition to challenges regarding hardware cost, complexity, special tooling, and access to adjust the actuator upon assembly. Accordingly, improved fluid injector actuators are desired to address the aforementioned problems and/or other problems in the art.